A. Field of the Invention
The device of the present invention relates generally to a new and improved organic composite electrical insulator system and to a new and improved method of manufacturing an organic composite electrical insulator system.
B. Description of the Prior Art
Electrical insulator systems for supporting compressive or tensile loads or for housing electrical components are old and well known in the art. Generally, such insulator systems include a centrally disposed core element and one or more integrally formed or nonintegral insulating elements, such as sheds, disposed about the central core element.
An example of a typical prior art electrical insulator system in the form of a suspension insulator is disclosed in United States patent application Ser. No. 576,731, filed on May 12, 1975 and assigned to the same assignee as the assignee of this application. The suspension insulator disclosed in that prior-filed patent application includes a centrally disposed resin bonded fiberglass rod and a plurality of serially disposed ceramic insulators or sheds disposed about and along the length of the fiberglass rod. The space between the inner surfaces of the sheds and the outer surface of the fiberglass rod is filled with an elastomeric filler, the thermal and mechanical characteristics of which must be taken into account due to the thickness of the filler.
The utility industry in the United States is now beginning to utilize organic electrical insulator systems for outdoor electrical transmission and distribution purposes. Some of the advantages of organic insulator systems are their lower weight, generally lower cost and, in some cases, increased strengths as compared to inorganic insulator systems, such as those systems employing ceramic sheds. U.S. Pat. Nos. 3,358,076; 3,735,019; and 3,898,372 disclose several different configurations of organic electrical insulator systems. The systems disclosed in the U.S. Pat. Nos. 3,735,019 and 3,898,372 utilize a central core member formed of resin-bonded glass fibers and a plurality of modular sheds formed with central apertures having inner diameters less than the outer diameters of the core members to retain and seal the sheds on the core members.
These prior art patents disclose the use of insulating grease or adhesive to enable the sheds to be slipped over the rod to their final desired position and to seal the interface surfaces to prevent the formation of air voids and the resultant deterioration of the insulator systems.
One major disadvantage of the organic composite insulator systems disclosed in these patents is that the grease or adhesive may separate from portions of the interface surfaces between the core members and the sheds to thereby form air voids and regions of reduced electrical strength, resulting in a reduction of the electrical impulse strength of the electrical insulator systems.